Engine Problems 454 Chev

Recently, I purchased a Winnebago Motor Home powered by a 454 Chev engine coupled to a TH400 auto transmission. I purchased this motor home knowing it had a leaking rear main seal but thinking, as shade tree mechanics do, it would be a snap to repair. Low and behold to my surprise, I found the crankshaft had thrusted so badly the thrust bearing was worn almost completely away as well as the crankshaft thrust collar badly scarred. After many questions asked and many bulletins read, the only explanation I was able to acquire was ballooning of the torque convertor creating forward pressure on the crankshaft but, after sending the torque convertor to a remanufacturer capable of checking this out, they say its possible but not with this one, it looks brand new. Ideas from mechanics or anyone who may have experienced this type problem would be greatly appreciated. Need help! river rat

Gary B

Senior Member
Engine Problems 454 Chev

Hi river rat, my guess would be that since your current torque converter seems almost new, a previous owner had a problem and replaced the torque converter but did nothing with the crankshaft, probaly didn't even realize there was a problem. Good luck.
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Engine Problems 454 Chev

Thanks Gary B. for your reply. This rv was purchased new by a minister friend of mine in 1988. He used it very little, complained to the dealership many times about the leak, however, was told about the history of 454 main seals leaks to explain the problem away. No repairs was ever made. It had 11,900 miles on it when I purchased (1) yr. ago. It ran and drove excellent, no engene noise, no hint of a problem other than the leak had I not decided to replace the seal. A family member who owns an auto machine shop has given me several bulletins addressing the problem but all indicate a ballooning of the convertor. I very much want to repair it but I,d like to be able to assure myself it won,t happen again. I was hoping someone had maybe experienced the same type problem. Thanks, river rat.
Engine Problems 454 Chev

Torque convertor balloning hmmmmm. that would take a lot of pressure for one.

My thoughts would be more along the line of the main shaft of the trans. bottoming out in the convertor prior when it gets hot.

If the convertor ballons, swells or what ever you call it it would have to thrust aganist the trans. main shaft.in order to push aganist the crank thrust. but the trans shaft is splined so that won't answer the question.

See if there are any service bulletins on this trans and contact a compat like Jasper engines or B&M transmissions

Has the thrust collar worn away or just the bearing.

Oh almost forgot another cause for thrust bearing wear is two fold, the crank shaft journal bearnings may be out of alignment (align boring needed) or too much initial clearance allowing the crank to pound aganist the bearing squishing out the oil film it suppose to ride on.